1. Field of the Invention
The present invention relates to an electrophotographic recording apparatus for use in copiers, facsimile equipment, optical printers, etc.
2. Prior Art
As a mainstream of conventional electrophotoelectric processes, zerography is known, which is basically divided into six processes. In other words, these six processes comprise a first process or charging a photosensitive device, a second process for exposing the photosensitive device by irradiating the same with light so as to form an electrostatic latent image, a third process for causing a toner to be adhered to the electrostatic latent image of this photosensitive device to effect development, a fourth process for transferring this development onto recording paper by making use of an electric field, a fourth process for fixing the image transferred onto the recording paper, and a six process for cleaning the toner remaining on the photosensitive device. Individual devices for effecting the first to fourth processes and the six process are disposed separately along a drum-like photosensitive device having a relatively large diameter or a sheet like photosensitive device, while a device for effecting the fifth process is disposed midway in a passage of transporting the recording paper (e.g., refer to R. M. Schaffert ("Electrophotography", published by The Focal Press (London and New York)).
In addition, as for the development device for the third process, a complicated mechanism requiring rotary mechanism parts having high precision, such as a magnet roll and a development sleeve have been employed (e.g., refer to Japanese Patent Publication No. 12148/1982).
As another method, there has been proposed a method whereby a transparent electrode is formed on a transparent substrate, such as glass, recording paper and a rear electrode plate are disposed in opposing and parallel relation thereto, a photoconductive toner layer charged on the transparent electrode is formed or transported, and charges are made to escape from the charged photoconductive toner to the transparent electrode by applying light from the rear surface of the transparent electrode, thereby transferring this selected toner to the recording paper and forming a visible image thereon (e.g., Japanese Patent Laid-Open No. 101424/1978).
In an apparatus based on the known zerography process, it is necessary to especially dispose devices for each process, so that the apparatus becomes complicated and large in size, which makes it difficult to make the apparatus thin and compact. Furthermore, the mechanism of the development device is complicated, and the toner during the development process comes into contact with the surface of the photosensitive device at a fast speed and causes friction therewith, thereby exerting an adverse effect on the life of the photosensitive device.
With respect to another method described above, there is a problem in that a special toner must be used which can be obtained by mixing zinc oxides, cadmium sulfide, etc. exhibiting photoconductive characteristics together with a binder, and such magnetic powders as magnetite at high temperature and by pulvering the mixture by means of a ball mill.
The present applicant has earlier proposed a novel electrophotographic process capable of substantially reducing the number of processes under Japanese Patent Application No. 99369/1985. An object of the present invention is to provide an electrophotographic recording apparatus which meets this method, requires a smaller area for a photosensitive device, is designed to prolong the life of the photosensitive device, requires no special toner, and is capable of easily effecting the charging of the toner.